In many use cases, it is necessary to estimate a bit rate of a digital signal. A bit rate is the number of bits that are conveyed or processed per unit of time. In networking and digital telecommunications, a bit rate refers to the per second measurement of data that passes through a communication channel of a communication network. In this context, a bit rate is synonymous with data transfer rate DTR. For multimedia encoding, a bit rate refers to the number of bits used per unit of playback time such as video or audio after data compression or encoding. Multimedia size and output quality often depends on the bit rate used during encoding. The speed at which audio and video size are encoded (compressed) can be measured in bits per second (bit rate). The speed at which data can be transferred within a computer or between a peripheral device and a computer can be measured in bytes per second indicating a data transfer rate. In digital communication systems, at the physical layer, the raw bit rate or gross rate comprises the total number of physically transferred bits per second over a communication link, including useful data as well as protocol overhead data. A gross bit rate is related to the symbol or modulation rate which is expressed in bauds or symbols per second. At the physical layer, the net bit rate of a digital communication channel is the capacity excluding the physical layer protocol overhead data such as time division multiplex framing bits or redundant forward error correction codes.
With increasing transfer rates and lower jitter margins, the performance of clock generation and recovery circuits becomes more important. The relevant factor in measuring jitter in general and jitter transfer in particular comprises the observed jitter transfer function of an instrument. Measuring devices, in particular oscilloscopes, are used for measuring jitter. Phase-locked loops can be used for digital estimations of signal rates or data transfer rates. Further, a bit rate can be estimated by counting signal flanks of digital signals. However, conventional bit rate estimation circuits provide a limited precision and are not robust against signal noise or signal disturbances, in particular at very high data transfer rates. Accordingly, there is a need to provide a method and apparatus providing a precise estimation of a bit rate of a digital signal even in a noisy environment.